install flatpak

 $ install flatpak
install: missing destination file operand after 'flatpak'
Try 'install --help' for more information.
dhwan@dhwan-Aspire-A514:~$ sudo apt install flatpak
[sudo] password for dhwan:
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  linux-headers-5.15.0-57-generic linux-headers-5.15.0-58-generic
  linux-hwe-5.15-headers-5.15.0-57 linux-hwe-5.15-headers-5.15.0-58
  linux-image-5.15.0-57-generic linux-image-5.15.0-58-generic
  linux-modules-5.15.0-57-generic linux-modules-5.15.0-58-generic
  linux-modules-extra-5.15.0-57-generic
  linux-modules-extra-5.15.0-58-generic
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  libappstream-glib8 libostree-1-1
The following NEW packages will be installed:
  flatpak libappstream-glib8 libostree-1-1
0 upgraded, 3 newly installed, 0 to remove and 23 not upgraded.
Need to get 1.484 kB of archives.
After this operation, 6.989 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://id.archive.ubuntu.com/ubuntu focal/main amd64 libappstream-glib8 amd64 0.7.16-1ubuntu1 [135 kB]
Get:2 http://id.archive.ubuntu.com/ubuntu focal/universe amd64 libostree-1-1 amd64 2020.3-1 [280 kB]
Get:3 http://id.archive.ubuntu.com/ubuntu focal-updates/universe amd64 flatpak amd64 1.6.5-0ubuntu0.4 [1.069 kB]
Fetched 1.484 kB in 9s (173 kB/s)  
Selecting previously unselected package libappstream-glib8:amd64.
(Reading database ... 408380 files and directories currently installed.)
Preparing to unpack .../libappstream-glib8_0.7.16-1ubuntu1_amd64.deb ...
Unpacking libappstream-glib8:amd64 (0.7.16-1ubuntu1) ...
Selecting previously unselected package libostree-1-1:amd64.
Preparing to unpack .../libostree-1-1_2020.3-1_amd64.deb ...
Unpacking libostree-1-1:amd64 (2020.3-1) ...
Selecting previously unselected package flatpak.
Preparing to unpack .../flatpak_1.6.5-0ubuntu0.4_amd64.deb ...
Unpacking flatpak (1.6.5-0ubuntu0.4) ...
Setting up libappstream-glib8:amd64 (0.7.16-1ubuntu1) ...
Setting up libostree-1-1:amd64 (2020.3-1) ...
Setting up flatpak (1.6.5-0ubuntu0.4) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for dbus (1.12.16-2ubuntu2.3) ...
Processing triggers for libc-bin (2.31-0ubuntu9.9) ...
dhwan@dhwan-Aspire-A514:~$ sudo apt remove gimp
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libgdcm3.0 libgmic1 libgraphicsmagick++-q16-12 libheif1 libmng2
  libmypaint-1.5-1 libmypaint-common libopencv-core4.2
  libopencv-imgcodecs4.2 libopencv-imgproc4.2 libopencv-videoio4.2
  libsocket++1 libtbb2 libtiff-tools linux-headers-5.15.0-57-generic
  linux-headers-5.15.0-58-generic linux-hwe-5.15-headers-5.15.0-57
  linux-hwe-5.15-headers-5.15.0-58 linux-image-5.15.0-57-generic
  linux-image-5.15.0-58-generic linux-modules-5.15.0-57-generic
  linux-modules-5.15.0-58-generic linux-modules-extra-5.15.0-57-generic
  linux-modules-extra-5.15.0-58-generic
Use 'sudo apt autoremove' to remove them.
The following packages will be REMOVED:
  gimp gimp-gmic gimp-plugin-registry
0 upgraded, 0 newly installed, 3 to remove and 23 not upgraded.
After this operation, 27,5 MB disk space will be freed.
Do you want to continue? [Y/n] y
(Reading database ... 408504 files and directories currently installed.)
Removing gimp-plugin-registry (9.20180625ubuntu2) ...
Removing gimp-gmic (2.4.5-1.1) ...
Removing gimp (2.10.18-1) ...
Processing triggers for desktop-file-utils (0.24-1ubuntu3) ...
Processing triggers for mime-support (3.64ubuntu1) ...
Processing triggers for gnome-menus (3.36.0-1ubuntu1) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for bamfdaemon (0.5.3+18.04.20180207.2-0ubuntu2) ...
Rebuilding /usr/share/applications/bamf-2.index...

dhwan@dhwan-Aspire-A514:~$ sudo apt install gnome-software-plugin-flatpak
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libgdcm3.0 libgmic1 libgraphicsmagick++-q16-12 libheif1 libmng2
  libmypaint-1.5-1 libmypaint-common libopencv-core4.2
  libopencv-imgcodecs4.2 libopencv-imgproc4.2 libopencv-videoio4.2
  libsocket++1 libtbb2 libtiff-tools linux-headers-5.15.0-57-generic
  linux-headers-5.15.0-58-generic linux-hwe-5.15-headers-5.15.0-57
  linux-hwe-5.15-headers-5.15.0-58 linux-image-5.15.0-57-generic
  linux-image-5.15.0-58-generic linux-modules-5.15.0-57-generic
  linux-modules-5.15.0-58-generic linux-modules-extra-5.15.0-57-generic
  linux-modules-extra-5.15.0-58-generic
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  gnome-software gnome-software-common gnome-software-plugin-snap
  libflatpak0 snapd
The following NEW packages will be installed:
  gnome-software gnome-software-common gnome-software-plugin-flatpak
  gnome-software-plugin-snap libflatpak0 snapd
0 upgraded, 6 newly installed, 0 to remove and 23 not upgraded.
Need to get 44,8 MB of archives.
After this operation, 185 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://id.archive.ubuntu.com/ubuntu focal-updates/main amd64 gnome-software-common all 3.36.1-0ubuntu0.20.04.1 [5.559 kB]
Get:2 http://id.archive.ubuntu.com/ubuntu focal-updates/main amd64 gnome-software amd64 3.36.1-0ubuntu0.20.04.1 [893 kB]
Get:3 http://id.archive.ubuntu.com/ubuntu focal-updates/universe amd64 libflatpak0 amd64 1.6.5-0ubuntu0.4 [276 kB]
Get:4 http://id.archive.ubuntu.com/ubuntu focal-updates/universe amd64 gnome-software-plugin-flatpak amd64 3.36.1-0ubuntu0.20.04.1 [97,2 kB]
Get:5 http://id.archive.ubuntu.com/ubuntu focal-updates/main amd64 snapd amd64 2.58+20.04 [37,9 MB]
Get:6 http://id.archive.ubuntu.com/ubuntu focal-updates/main amd64 gnome-software-plugin-snap amd64 3.36.1-0ubuntu0.20.04.1 [73,0 kB]
Fetched 44,8 MB in 37s (1.201 kB/s)                                      
Selecting previously unselected package gnome-software-common.
(Reading database ... 407933 files and directories currently installed.)
Preparing to unpack .../0-gnome-software-common_3.36.1-0ubuntu0.20.04.1_al
l.deb ...
Unpacking gnome-software-common (3.36.1-0ubuntu0.20.04.1) ...
Selecting previously unselected package gnome-software.
Preparing to unpack .../1-gnome-software_3.36.1-0ubuntu0.20.04.1_amd64.deb
 ...
Unpacking gnome-software (3.36.1-0ubuntu0.20.04.1) ...
Selecting previously unselected package libflatpak0:amd64.
Preparing to unpack .../2-libflatpak0_1.6.5-0ubuntu0.4_amd64.deb ...
Unpacking libflatpak0:amd64 (1.6.5-0ubuntu0.4) ...
Selecting previously unselected package gnome-software-plugin-flatpak.
Preparing to unpack .../3-gnome-software-plugin-flatpak_3.36.1-0ubuntu0.20
.04.1_amd64.deb ...
Unpacking gnome-software-plugin-flatpak (3.36.1-0ubuntu0.20.04.1) ...
Selecting previously unselected package snapd.
Preparing to unpack .../4-snapd_2.58+20.04_amd64.deb ...
Unpacking snapd (2.58+20.04) ...
Selecting previously unselected package gnome-software-plugin-snap.
Preparing to unpack .../5-gnome-software-plugin-snap_3.36.1-0ubuntu0.20.04
.1_amd64.deb ...
Unpacking gnome-software-plugin-snap (3.36.1-0ubuntu0.20.04.1) ...
Setting up snapd (2.58+20.04) ...
Created symlink /etc/systemd/system/multi-user.target.wants/snapd.aa-promp
t-listener.service → /lib/systemd/system/snapd.aa-prompt-listener.service.
Created symlink /etc/systemd/system/multi-user.target.wants/snapd.apparmor
.service → /lib/systemd/system/snapd.apparmor.service.
Created symlink /etc/systemd/system/multi-user.target.wants/snapd.autoimpo
rt.service → /lib/systemd/system/snapd.autoimport.service.
Created symlink /etc/systemd/system/multi-user.target.wants/snapd.core-fix
up.service → /lib/systemd/system/snapd.core-fixup.service.
Created symlink /etc/systemd/system/multi-user.target.wants/snapd.recovery
-chooser-trigger.service → /lib/systemd/system/snapd.recovery-chooser-trig
ger.service.
Created symlink /etc/systemd/system/multi-user.target.wants/snapd.seeded.s
ervice → /lib/systemd/system/snapd.seeded.service.
Created symlink /etc/systemd/system/cloud-final.service.wants/snapd.seeded
.service → /lib/systemd/system/snapd.seeded.service.
Created symlink /etc/systemd/system/multi-user.target.wants/snapd.service
→ /lib/systemd/system/snapd.service.
Created symlink /etc/systemd/system/timers.target.wants/snapd.snap-repair.
timer → /lib/systemd/system/snapd.snap-repair.timer.
Created symlink /etc/systemd/system/sockets.target.wants/snapd.socket → /l
ib/systemd/system/snapd.socket.
Created symlink /etc/systemd/system/final.target.wants/snapd.system-shutdo
wn.service → /lib/systemd/system/snapd.system-shutdown.service.
snapd.failure.service is a disabled or a static unit, not starting it.
snapd.mounts-pre.target is a disabled or a static unit, not starting it.
snapd.mounts.target is a disabled or a static unit, not starting it.
snapd.snap-repair.service is a disabled or a static unit, not starting it.
Setting up gnome-software-common (3.36.1-0ubuntu0.20.04.1) ...
Setting up gnome-software (3.36.1-0ubuntu0.20.04.1) ...
Setting up libflatpak0:amd64 (1.6.5-0ubuntu0.4) ...
Processing triggers for bamfdaemon (0.5.3+18.04.20180207.2-0ubuntu2) ...
Rebuilding /usr/share/applications/bamf-2.index...
Processing triggers for desktop-file-utils (0.24-1ubuntu3) ...
Processing triggers for mime-support (3.64ubuntu1) ...
Processing triggers for hicolor-icon-theme (0.17-2) ...
Processing triggers for gnome-menus (3.36.0-1ubuntu1) ...
Processing triggers for libglib2.0-0:i386 (2.64.6-1~ubuntu20.04.4) ...
Processing triggers for libglib2.0-0:amd64 (2.64.6-1~ubuntu20.04.4) ...
Processing triggers for libc-bin (2.31-0ubuntu9.9) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for dbus (1.12.16-2ubuntu2.3) ...
Setting up gnome-software-plugin-flatpak (3.36.1-0ubuntu0.20.04.1) ...
Setting up gnome-software-plugin-snap (3.36.1-0ubuntu0.20.04.1) ...
dhwan@dhwan-Aspire-A514:~$ flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo

Note that the directories

'/var/lib/flatpak/exports/share'
'/home/dhwan/.local/share/flatpak/exports/share'

are not in the search path set by the XDG_DATA_DIRS environment variable,
so applications installed by Flatpak may not appear on your desktop until
the session is restarted.

dhwan@dhwan-Aspire-A514:~$